North Loup River-Middle Loup River drainage divide area landform origins in Valley, Sherman, and Howard Counties, Nebraska, USA

· Loup River, Nebraska
Authors

A geomorphic history based on topographic map evidence

Abstract:

The North Loup River-Middle Loup River drainage divide area in Valley, Sherman, and Howard Counties was eroded by immense southeast-oriented floods, which eroded the southeast-oriented North and Middle Loup River valleys headward from what was a newly eroded and large northeast-oriented Loup River-Platte River valley. Evidence supporting the southeast-oriented flood interpretation includes the North and Middle Loup River valley orientations, barbed tributaries, orientations of the North and Middle Loup River tributary valleys, anastomosing channel complexes, and shallow through valleys eroded across present day North and Middle Loup River tributary drainage divides. Prior to headward erosion of what was then a deep and wide northeast-oriented Loup River-Platte River valley flood waters in the North Loup River-Middle Loup River flowed across a topographic surface at least as high as the highest drainage divide area elevations today, if not higher. It is possible flood waters were ponded where east and northeast oriented flood waters from the west converged with southeast-oriented flood water from the northwest. If so flood waters may have deposited significant sediment in the North Loup River-Middle Loup River drainage divide area, which was subsequently deeply eroded during final flood events.

Preface:

The following interpretation of detailed topographic map evidence is one of a series of essays describing similar evidence for all major drainage divides contained within the Missouri River drainage basin and for all major drainage divides with adjacent drainage basins. The research project is interpreting evidence in the context of a previously unexplored deep glacial erosion paradigm, which is fundamentally different from most commonly accepted North American glacial history interpretations. Project essays are listed on the sidebar category list under their appropriate Missouri River tributary drainage basin, Missouri River segment drainage basin (by state), and/or state in which the Missouri River drainage basin is located.                  

Introduction:

  • The purpose of this essay is to use topographic map interpretation methods to explore North Loup River-Middle Loup River drainage divide area landform origins in Valley, Sherman, and Howard Counties, Nebraska, USA. Map interpretation methods can be used to unravel many geomorphic events leading up to formation of present-day drainage routes and development of other landform features. While each detailed topographic map feature provides detailed evidence to be explained, the solution must be consistent with explanations for adjacent area map evidence as well as solutions to big picture map evidence puzzles. I invite readers to improve upon my solutions and/or to propose alternate solutions that better explain evidence and are also consistent with adjacent map area and big picture evidence. Readers may do so either by making comments here or by writing and publishing their own essays and then by leaving a link to those essays in a comment here.
  • This essay is also exploring a new geomorphology paradigm in which erosional landforms are interpreted as evidence left by immense glacial melt water floods. Implied in that interpretation is the immense floods were derived from a thick North American ice sheet that created a deep “hole” in the North American continent and also melted fast. The previously unexplored paradigm being tested in this and other Missouri River drainage basin landform origins research project essays is a thick North American ice sheet, comparable in thickness to the Antarctic ice sheet, occupied the North American region usually recognized to have been glaciated, and through its weight and erosive actions created a deep North American “hole”. The southwestern rim of that deep “hole” is today preserved in the high Rocky Mountains. The ice sheet through its weight and deep erosion (and perhaps deposition along major south-oriented melt water flow routes) caused significant crustal warping and tectonic change, through its action of melting fast produced immense floods that flowed across the continent, and through its action of melting fast systematically opened up space in the ice sheet created “hole” so headward erosion of newly developed north-oriented drainage systems captured immense south-oriented melt water floods and diverted the floods north into space the ice sheet had once occupied.
  • If this previously unexplored paradigm is correct the geographic region explored by this essay should contain evidence of immense floods that were captured by headward erosion of new valley systems so as to cause the floods to flow in a different direction. Ability of this previously unexplored paradigm to explain North Loup River-Middle Loup River drainage divide area landform origins in Valley, Sherman, and Howard Counties, Nebraska will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm. This essay is included in the Missouri River drainage basin landform origins research project essay collection.

North Loup River-Middle Loup River drainage divide area location map

Figure 1: North Loup River-Middle Loup River drainage divide area location map (select and click on maps to enlarge). National Geographic Society map digitally presented using National Geographic Society TOPO software.

Figure 1 provides a North Loup River-Middle Loup River drainage divide area in Valley, Sherman, and Howard Counties location map. Most of the figure 1 map area is located in central and eastern Nebraska, with the west to east oriented Nebraska-Kansas state line located near the figure 1 south edge. Also, in the figure 1 northeast corner the south-southeast oriented Missouri River marks the boundary between Nebraska and Iowa. The major Nebraska river shown is the Platte River, which flows from North Platte (near the figure 1 west center edge) in a southeast direction to Kearney and then turns to flow in a northeast direction to Columbus and North Bend. At North Bend the Platte River turns to flow to Fremont and then turns to flow south before turning to flow east to join the south-southeast oriented Missouri River east of the figure 1 map area. The Loup River is a northeast oriented Platte River tributary and joins the Platte River near Columbus. Almost all Loup River tributaries shown in figure 1 are southeast-oriented and from east to west include Beaver Creek, which flows through Albion and St Edward before joining the Loup River near Genoa; Cedar River (unlabeled in figure 1), which flows through Ericson, Spalding, and Cedar Rapids before joining the Loup River near Fullerton; The North Loup River, which flows from the figure 1 northwest corner area through Brewster, Burwell, Ord, and Elba before joining the Loup River north of St Paul; the Middle Loup River, which also flows from the figure 1 northwest corner area through Seneca,Thedford, Sargent, Comstock and Loup City before joining the Loup River near Boelus; Cedar Creek, which flows through Litchfield and Hazard before joining the Loup River near Ravenna; and the South Loup River, which flows in a southeast direction from Stapleton before turning to flow in a northeast direction at Pleasanton. This essay addresses the North Loup River-Middle Loup River drainage divide downstream from the Comstock and Ord areas. The Loup River-Platte River drainage divide area essay describes the region to the south, the Cedar River-North Loup River drainage divide area essay describes the region to the east, and the Elkhorn River-Loup River drainage divide area and the Niobrara River-North Loup River drainage divide area essays describe the region to the north and northwest and these and other Loup River drainage basin drainage divide area essays can be found under Loup River on the sidebar category list. Hundreds of other Missouri River drainage basin landform origins research project essays published on this website have presented overwhelming evidence for an immense southeast-oriented flood that flowed across central and eastern Nebraska to converge with a large east-oriented flood flowing in what was then the newly eroded and large northeast and east oriented Loup River-Platte River valley.

North Loup River-Middle Loup River drainage divide area detailed location map

Figure 2: North Loup River-Middle Loup River drainage divide area detailed location map. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 2 provides a more detailed location map for the North Loup River-Middle Loup River drainage divide area located in Valley, Sherman, and Howard Counties. Valley, Greeley, Boone, Sherman, Howard, Nance, Merrick, and Hamilton are Nebraska county names and the county boundaries are shown. Custer County is the county located west of Valley and Sherman Counties and Buffalo County is the county south of Sherman County. The northeast oriented Platte River forms the Merrick County-Hamilton County border in the figure 2 southeast corner. The South Loup River flows in a southeast direction from the figure 2 west edge in southern Custer County to Pleasanton in northern Buffalo County. At Pleasanton the South Loup River turns to flow in a northeast direction and to become the northeast oriented Loup River, which joins the Platte River east of the figure 2 map area. The North Loup River flows from the figure 2 northwest corner to Burwell (located just north of the Valley County northeast corner) and then flows in a southeast direction through Valley County, across the Greeley County southwest corner, and into Howard County where it joins the northeast oriented Loup River. The Middle Loup River flows in an east direction across northern Custer County before turning southeast to flow to Comstock and across the Valley County southwest corner and diagonally across Sherman County before joining the northeast-oriented Loup River near Boelus (Howard City) in the Howard County southwest corner. Named North Loup River tributaries important here include Munson Creek, Davis Creek, South and North Branches of Mira Creek, and South and North Branches of Turtle Creek. Hayes Creek is the only named Middle Loup River tributary discussed below, although detailed maps below show other named North and Middle Loup River tributaries. One remarkable features of the figure 2 map area is the predominately southeast-oriented drainage routes flowing to the northeast-oriented Loup River. Southeast of the northeast-oriented Loup River the drainage routes are oriented in a northeast direction, at least north of the northeast-oriented Platte River, which flows in the same wide northeast-oriented valley as the northeast-oriented Loup River. The Loup River flows along the valley’s northwest wall and the Platte River flows along the valley’s southeast wall. What has happened here is a large southeast-oriented flood has merged with a large northeast-oriented flood. The northeast-oriented flood was located in the Platte River valley and flood waters came from west of the figure 2 map area. The southeast-oriented flood flowed in a southeast direction across the entire figure 2 map area to what was then the newly eroded northeast- and east-oriented Platte River valley. Southeast-oriented flood waters flowing into the northeast-oriented valley were forced to flow along the valley’s northwest wall while flood waters from the west flowed along the valley’s southeast wall.

Southeast end of North Loup River-Middle Loup River drainage divide area

Figure 3: Southeast end of North Loup River-Middle Loup River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 3 uses reduced size maps to illustrate the southeast end of the North Loup River-Middle Loup River drainage divide area. St Paul is the larger town located near the figure 3 east edge and the Loup River is the river flowing in a northeast direction along the south side of St Paul. The southeast oriented North Loup River is located in the figure 3 northeast quadrant and joins the Loup River just east of the figure 3 map area. Elba is the town located in the North Loup River valley in the figure 3 northeast quadrant. Munson Creek is the southeast and east oriented North Loup River tributary joining the North Loup River near Elba (figure 4 illustrates the Munson Creek area in more detail). Loup City is located in the figure 3 northwest corner area and the Middle Loup River is the southeast-oriented river flowing from the figure 3 northwest corner to join the northeast-oriented Loup River near the figure 3 south center edge. Boelus (or Howard City) is the town located near where the Middle Loup River enters the northeast-oriented Loup River. The lake located in the figure 3 northwest quadrant is Sherman Reservoir and the stream flowing in a southeast direction from Sherman Reservoir is Oak Creek. Ashton is the town located in the Oak Creek valley a short distance downstream from Sherman Reservoir. The Loup River in this area is flowing along the northwest wall of the large northeast-oriented Loup River-Platte River valley, with the Platte River (not seen in figure 3) flowing near the valley’s southeast wall (see Loup River-Platte River drainage divide area essay). Note how almost all drainage routes in the North Loup River-Middle Loup River drainage divide area are southeast-oriented and parallel the southeast-oriented North Loup River and Middle Loup River orientations. This remarkable drainage alignment developed when southeast-oriented flood waters flowing into what was a newly eroded and deep northeast-oriented Loup River-Platte River valley eroded southeast-oriented valleys headward along the southeast-oriented flood flow routes. These southeast-oriented valleys could not be eroded until headward erosion of the deep northeast-oriented Loup River-Platte River valley created a lower base level. Prior to that time flood waters flowed southeast across the entire figure 3 map area on an upland topographic surface at least as high as the highest figure 3 elevations today. Figure 3 drainage divides today preserve remnants of the upland erosion surface created by those earlier southeast-oriented flood waters.

Munson Creek-Auger Creek drainage divide area

Figure 4: Munson Creek-Auger Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 4 illustrates the Munson Creek-Auger Creek drainage divide area seen is less detail in the figure 3 northeast quadrant. St Paul is the town located in the figure 4 southeast quadrant. The Loup River flows in a northeast direction in the figure 4 southeast corner. Turkey Creek flows in a south-southeast direction in the figure 4 southwest corner. The North Loup River flows in a south-southeast direction from the figure 4 north edge to the east edge north of St Paul. Elba is the town located in the North Loup River valley. Munson Creek is the southeast oriented stream flowing from the figure 4 northwest corner area that upon entering the North Loup River valley near Elba turns to flow in a northeast direction to join the southeast oriented North Loup River as a barbed tributary. Immediately south of Munson Creek in the figure 4 southeast corner is north oriented Auger Creek, which upon entering the North Loup River valley turns to flow in a northeast direction to also join the North Loup River as a barbed tributary. Note in the figure 4 southeast corner how another unnamed stream also flows to the North Loup River as a barbed tributary. How does a south-southeast oriented river like the North Loup River acquire multiple north and northeast oriented tributaries? Think of the figure 4 region just prior to headward erosion of the deep North Loup River valley. At that time the entire figure 4 map area was at an elevation equivalent to the elevation of the present day figure 4 drainage divide elevations, if not higher. Also at that time an immense south-southeast oriented flood was moving across the entire figure 4 map area to what was then the newly eroded northeast-oriented Loup River-Platte River valley to the south. Flood waters were eroding a complex of shallow south and southeast oriented anastomosing channels into that upland erosion surface. Headward erosion of the southeast oriented North Loup River valley then entered the figure 4 map area and began to behead (one by one) the south and south-southeast oriented flood flow channels. Flood waters in the north ends of the beheaded flood flow channels reversed flow direction to flow north to the newly eroded and deeper southeast-oriented North Loup River valley. Because the flood flow channels were beheaded one by one in sequence from east to west and because the channels were anastomosing (interconnected), reversed flow in one channel could capture yet to be beheaded flood flow from adjacent channels (further to the west). For example, note the southeast-oriented Auger Creek tributary located west of the north-oriented Auger Creek valley. Also, note how the north-northeast Munson Creek valley segment appears to have captured the southeast- and east-oriented Munson Creek valley further to the west.

North and South Branches of Mira Creek-Davis Creek drainage divide area

Figure 5: North and South Branches of Mira Creek-Davis Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 5 illustrates drainage divides between the North and South Branches of Mira Creek and between the South Branch Mira Creek and Davis Creek and is located north and west of the figure 4 map area. The North Loup River flows from the figure 5 north edge (east end) to the figure 5 east edge (south end). North Loup is the town located in the figure 5 northeast quadrant and Scotia is the smaller town located near the figure 5 east center edge. The east-oriented stream flowing just north of North Loup is Mira Creek. The North Branch Mira Creek flows from the figure 5 northwest corner along the north edge before turning to flow in a southeast direction to join the South Branch and then to flow in east direction to join the North Loup River. The South Branch Mira Creek originates as a southeast-oriented stream, but then changes direction to flow in a northeast direction to join the North Branch and then flow east to the North Loup River. Note how the drainage divide area between the North Branch valley (in the figure 5 northwest quadrant) and the southeast-oriented South Branch headwaters valleys includes multiple northwest-southeast oriented through valleys with northwest-southeast oriented streamlined erosional residuals. These through valleys and streamlined erosional residuals are evidence of southeast-oriented flood flow routes that existed prior to headward erosion of the east-oriented North Branch valley. Flood waters were flowing to what was then the newly eroded South Branch valley. Further to the south in the figure 5 map area is Davis Creek. Davis Creek originates near the figure 5 west center edge and flows in a southeast direction to the figure 5 southeast quadrant, where Davis Creek turns to flow in a northeast and east direction to join the southeast-oriented North Loup River. A close look at the Davis Creek headwaters area near the figure 5 west edge reveals multiple through valleys linking the southeast-oriented Davis Creek headwaters with north and northeast oriented North Branch Mira Creek tributaries and also with north and northeast oriented South Branch Mira Creek tributaries. Continuing east along the South Branch-Davis Creek drainage divide there are many additional through valleys linking the two present day independent drainage basins. The through valleys provide evidence that prior to headward erosion of the South Branch Mira Creek valley multiple flood flow channels moved flood waters to what was then the newly eroded Davis Creek valley. Figure 6 provides a more detailed look at the Davis Creek headwaters area.

Detailed map of North Branch-South Branch Mira Creek-Davis Creek drainage divide area

Figure 6Detailed map of North Branch-South Branch Mira Creek-Davis Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 6 provides a more detailed map of the Davis Creek headwaters area seen in less detail near the figure 5 west center edge area. Davis Creek headwaters are located in sections 8 and 9 and flow in a southeast direction to the figure 6 south edge. North-oriented drainage in the figure 6 northwest corner and in section 5 along the figure 6 north edge flows to the North Branch Mira Creek while north-oriented drainage in section 4 is the headwaters of the South Branch Mira Creek. The South Branch Mira Creek flows along the figure 6 north edge in section 3 and then is labeled in section 2 in the figure 6 northeast corner. Note how multiple north-south through valleys link headwaters of the north-oriented North Branch Mira Creek tributary with the southeast-oriented Davis Creek headwaters. Also note how multiple through valleys at various elevations link north-oriented South Branch Mira Creek tributary valleys with south oriented Davis Creek tributary valleys. These through valleys, while perhaps not spectacular, are evidence of multiple south oriented flood flow routes that existed prior to headward erosion of the South and North Branch Mira Creek valleys. The sequence of figure 6 valley formation can be determined. Prior to any headward erosion of present day valleys flood waters flowed south or southeast across the entire figure 6 map area on a topographic surface at least as high as the highest figure 6 elevations today. The Davis Creek valley was the first valley to erode headward into the figure 6 region. Headward erosion of the Davis Creek valley captured the south or southeast oriented flood flow and diverted the flood waters southeast and east to what was then the newly eroded North Loup River valley. Headward erosion of the South Branch Mira Creek valley occurred next and beheaded flood flow routes to all but the western end of the newly eroded Davis Creek valley. Flood waters on the north ends of the beheaded flood flow routes reversed flow direction to flow north to South Branch Mira Creek valley. Headward erosion of the North Branch Mira Creek valley then beheaded flood flow routes to the newly eroded South Branch Mira Creek valley and also to the Davis Creek valley west end. Flood waters on the north ends of beheaded flood flow routes reversed flow direction to flow north to newly eroded North Branch Mira Creek valley.

Turtle Creek-Dane Creek drainage divide area

Figure 7: Turtle Creek-Dane Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 7 illustrates the Turtle Creek-Dane Creek drainage divide north and west of the figure 5 map area. The North Loup River flows in a southeast direction from the figure 7 north edge (east end) to the figure 7 east edge (south half). Ord is the town located near where the North Loup River crosses the figure 7 east edge. Dane Creek is the north-oriented (barbed) tributary flowing to the North Loup River near Ord. Note how Dane Creek headwaters are southeast oriented and in the figure 7 southeast quadrant Dane Creek makes a U-turn from flowing southeast to flowing north. North of the southeast oriented Dane Creek headwaters are north-oriented headwaters of the South Branch of Turtle Creek. Turtle Creek flows east to join the North Loup River in the figure 7 northeast quadrant. The North Branch Turtle Creek flows northeast in the figure 7 northwest quadrant and then flows east along the figure 7 north center edge before turning southeast to join the north-oriented South Branch and then to flow east to the North Loup River. Note how a large north-south through valley links the north-oriented South Branch Turtle Creek valley with the southeast oriented Dane Creek headwaters valley. Also note the multiple northwest-southeast oriented through valleys in the GERANIUM township area linking the North Branch Turtle Creek valley with both the north-oriented South Branch Turtle Creek headwaters which originate near the figure 7 south center edge.These northwest-southeast and north-south oriented through valleys provide evidence that large volumes of southeast and/or south oriented flood flow deeply eroded the figure 7 map area prior to headward erosion of the east-oriented North Branch Turtle Creek valley. The north-oriented Dane Creek valley segment originated as a south oriented flood flow route, which was beheaded by headward erosion of the deep southeast-oriented North Loup River valley. Flood waters on the north end of the beheaded flood flow route reversed flow direction to flow north to the newly eroded and deeper North Loup River valley. The reversed flood flow captured significant south- and southeast-oriented flood water flow routes from the west. Headward erosion of the North Loup River-Turtle Creek valley then beheaded south-oriented flood flow on what is now the South Branch Turtle valley route. Flood waters on the north end of that beheaded flood flow route reversed flow direction to flow north to the newly eroded Turtle Creek valley. Next headward erosion of the North Branch Turtle Creek valley beheaded southeast-oriented flood flow routes in the figure 7 northwest quadrant.

Middle Loup River-Dane Creek drainage divide area

Figure 8: Middle Loup River-Dane Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 8 illustrates the Middle Loup River-Dane Creek drainage divide area west of the figure 7 map area and includes overlap areas with figure 7. The Middle Loup River flows southeast from the figure 8 west edge (north half) and then south-southeast to the figure 8 south edge (west half). The north-south Custer County-Valley County border is located just east of where the Middle Loup River crosses the figure 8 south edge. Comstock is the town located in the Middle Loup River valley. Southeast oriented Dane Creek headwaters can be seen in the figure 8 east center edge area and north of the Dane Creek headwaters is the north-oriented South Branch Turtle Creek. Southeast and northeast oriented North Branch Turtle Creek headwaters are located near the figure 8 north center edge (northwest of the word GERANIUM). Cottonwood Creek is the named south-oriented Middle Loup River tributary located in the figure 8 south center area. Hawthorne Creek is a south-oriented (and southwest-oriented south of the figure 8 map area) Middle Loup River tributary located in the figure 8 southeast quadrant (near the south edge). Woods Park north of Comstock is an interesting erosional basin, which is linked by through valleys to the south-oriented Middle Loup River tributary, The Middle Loup River-North Loup River drainage divide in figure 8 appears to be a northwest-southeast oriented escarpment 50 or more meters high. This escarpment is probably a southwest wall of a large southeast-oriented flood eroded valley to the northeast. Apparently this entire region was/is covered with easily eroded materials that southeast-oriented flood waters were able to flush from the region as the North Loup River valley was eroding to the northwest. Headward erosion of the North Branch Turtle Creek valley probably captured the southeast-oriented flood flow before all material could be flushed from the region. The Woods Park basin probably was formed in a similar manner, with south-oriented flood water flushing easily eroded material southward in the through valleys to the south to what was then the actively eroding Middle Loup River valley. Note shallow north-south through valleys linking the North Loup River drainage basin northeast of the northeast-facing escarpment with the south-oriented Cottonwood and Hawthorne Creek valleys. Those through valleys provide evidence that prior to headward erosion of the southeast-oriented valley (of which the escarpment is the southwest wall), flood waters flowed south from the present day North Loup River drainage basin to what were then the actively eroding Cottonwood Creek and Hawthorne Creek valleys (suggesting the North Loup River valley and the Middle Loup River valley eroded headward at approximately the same time)..

Detailed map of Woods Park-Middle Loup River drainage divide area

Figure 9: Detailed map of Woods Park-Middle Loup River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 9 provides a detailed map of the Woods Park-Middle Loup River drainage divide area northeast of Comstock that was seen in less detail in the figure 8 map above. The south-southeast oriented Middle Loup River is located in the figure 9 southwest corner. Woods Park is the basin located in the figure 9 north central area and along the figure 9 north edge. Note how drainage in section 30 is the northwest-oriented or toward the center of Woods Park and how drainage in section 23 is to the southwest to the south-southeast oriented Middle Loup River valley. These present day drainage routes, while not continuous surface drainage routes, provide evidence final flood water movement in the Woods Park basin was in a northwest direction across Woods Park and then in a southwest direction through the valley in the section 23 southwest corner to the south-southeast oriented Middle Loup River. However, before the final flood movement, flood flow movement in Woods Park was to the southeast and south via the through valleys located in sections 32, 31, and 30. The deepest of the through valleys is located in section 31 northeast corner and probably represents the final south-oriented flood flow route. South-oriented flood flow across the Woods Park basin was beheaded by headward erosion of the Middle Loup River valley and by headward erosion of the Big Oak Canyon valley system just north of the figure 9 map area. Figure 9a below illustrates that Big Oak Canyon drainage system and how a Big Oak Canyon tributary flows in a west direction along the ridge just north of Woods Park. The Woods Park basin may be a south-oriented headcut eroded into easily eroded material where south oriented flood waters initially flowed south using the though valleys seen in figure 9 above and southwest to the what was then the newly eroded Middle Loup River valley using the valley in the section 23 southwest corner. The rugged topography north of Woods Park and then the smoother upland surface in the figure 9a north center area suggests easily eroded material has been partially removed from the region north of Woods Park, with remnants of the material still remaining. It is possible the easily eroded material was deposited during early flood stages, when flood waters may have been ponded in this region. Ponding may have occurred because an immense southeast-oriented flood was converging with a large east-oriented flood in the Loup River-Platte River valley area to the southeast. If so, following headward erosion of the deep northeast-oriented Loup River-Platte River valley, the related headward erosion of the deep Middle Loup River valley may have lowered the regional base level sufficiently to deeply erode the previously deposited flood transported sediment.

Figure 9a: Big Oak Canyon drainage system north of Woods Park (note unnamed west-oriented Oak Canyon tributary in sections 11 and 12).  United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Hawthorne Creek-Hays Creek drainage divide area

Figure 10: Hawthorne Creek-Hays Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 10 illustrates the Hawthorne Creek-Hays Creek drainage divide area south and east of the figure 8 map area, west of the figure 5 map area, and includes overlap areas with figures 8 and 5. The Middle Loup River flows in a southeast direction in the figure 10 southwest corner area. Arcadia is the town located in the Middle Loup River valley. Cottonwood Creek is the south and southwest oriented stream located in the figure 10 northwest corner. Hawthorne Creek is the south and southwest oriented stream entering the Middle Loup River valley north of Arcadia. Hays Creek flows southeast and south-southwest in the figure 10 south center area. The northeast and east oriented stream in the figure 10 northeast quadrant is the North Branch Mira Creek. Southeast-oriented headwaters of Davis Creek are located in the figure 10 southeast quadrant. A close look at the figure 10 map area reveals anastomosing channel complexes in many of the south-oriented Middle Loup River tributary drainage basins in addition to through valleys linking those drainage basins with each other and also with the North Loup River tributary drainage basin to the east. Figure 10a below provides a detailed map of the Hays Creek drainage basin to illustrate the anastomosing channel complex and streamlined erosional residuals present there. Note how Hays Creek is flowing south in a maze of intertwined valleys with northwest-southeast oriented erosional residuals located between the flood flow channels. This anastomosing channel complex, like other anastomosing channel complexes in the Middle Loup River drainage basin (and the North Loup River drainage basin) provides evidence the North Loup River-Middle Loup River drainage divide area was eroded by immense southeast-oriented floods. As described in the North Loup River drainage basin, evidence that headward erosion of the Middle Loup River and of the Middle Loup River tributary valleys beheaded flood flow to newly eroded tributary valleys further to the southeast and south.

Figure 10a: Anastomosing channel complex in Hays Creek drainage basin. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Additional information and sources of maps studied

This essay has provided only a sample of the detailed topographic map evidence supporting the flood erosion interpretation. Many additional illustrations could be provided. Readers are encouraged to look at mosaics of detailed topographic maps to see the abundance of available data. Maps used in this study were created and published by the United States Geologic Survey and can be obtained directly from the United States Geological Survey and/or from dealers offering United States Geological Survey maps. Hard copy maps can also be observed at United States Geological Survey map depositories which are located throughout the United States and elsewhere. Illustrations used here were created using National Geographic Society TOPO software and digital map data. TOPO software and map data can be obtained from the National Geographic Society and/or dealers offering National Geographic Society digital map data.

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